Serous effusions are rare extramedullary manifestations of pediatric acute myeloid leukemia (AML), for which limited data are available. This study aimed to systematically characterize the clinical features, biological profiles, and outcomes of pediatric AML patients who presented with serous effusions. A retrospective case series was conducted at Beijing Children’s Hospital and Beijing Children’s Hospital Baoding Hospital from January 2015 to December 2024. Pediatric patients newly diagnosed with AML or isolated myeloid sarcoma presenting with serous effusion were included. Seven children (six males and one female) were included. The median time from symptom onset to diagnosis was 30 days (range: 10–150 days). Initial white blood cell counts ranged from 3.39 × 10⁹/L to 212.13 × 10⁹/L, with two patients exhibiting hyperleukocytosis. Genetic alterations included KMT2A rearrangements (4/7), RUNX1::RUNX1T1 fusions (2/7), and SFPQ::ZFP36L2 fusion (1/7). All patients had pleural effusions, and six had pericardial effusion. Four patients had additional extramedullary involvement. The median follow-up was 12.0 months (range: 1.0–68.0 months). Owing to critical illness, six of the seven patients received induction therapy in the intensive care unit. One patient died after induction therapy because of severe acute suppurative appendicitis and sepsis; the remaining six patients underwent hematopoietic stem cell transplantation. At the last follow-up, four patients were alive, while two died of early relapse following stem cell transplantation. Serous effusion is a rare manifestation of pediatric AML, which is observed in patients with high-risk genetics and is often accompanied by a critical clinical course necessitating intensive care. Further studies are needed in this subgroup.

The application of targeted therapy with arsenic and all-trans retinoic acid (ATRA) has significantly improved outcomes in pediatric acute promyelocytic leukemia (APL), but relapse remains a major obstacle to cure. This study aimed to identify risk factors for relapse in pediatric APL and to evaluate the relationship between arsenic concentration and relapse. In this multicenter retrospective study, a total of 566 pediatric patients with newly diagnosed APL treated with the CCLG-APL 2016 or CCLG-APL 2018 protocol were enrolled. The median follow-up was 68.0 months, and 44 patients experienced relapse. The analysis showed complex karyotypes (≥ 3 additional chromosomal abnormalities) (HR = 3.238, 95% CI: 1.134–9.244, P = 0.028) and MCR ≥ 72 days (HR = 1.995, 95% CI: 1.132–3.757, P = 0.024) were independent risk factors for relapse. Logistic regression indicated that arsenic trioxide (ATO) used during induction was associated with a lower relapse risk compared to Realgar-Indigo naturalis formula (RIF) (OR = 0.310, 95% CI: 0.105–0.916, P = 0.034]. In 64 patients with arsenic monitoring, blood arsenic levels on days 7, 14, and 28 were significantly higher in ATO group than the RIF group (all P < 0.01), and were significantly lower in the relapse group compared to the non-relapse group ( P = 0.031, 0.036, 0.034, respectively). ROC analysis identified a blood arsenic cutoff of < 25.6 ng/mL after 7 days of induction as predictive of higher relapse risk. Our study confirmed risk factors for relapse in pediatric APL, and suggested that maintaining a blood arsenic concentration ≥ 25.6 ng/mL after seven days of induction may be beneficial for prognosis.

Objective: This study aims to evaluate patient-reported quality of life (QoL) in children with Ph-negative B-cell acute lymphoblastic leukemia (B-ALL) who received first-line treatment with blinatumomab in the CCLG-ALL 2018 supplementary study (ChiCTR2400083570). Methods: CCLG-ALL 2018 supplementary study evaluated the outcomes of blinatumomab in combination with chemotherapy for intermediate risk (MR) and high risk (HR) patients.MR patients received 14 days of blinatumomab (replacing induction) after a 15-day chemotherapy induction, while HR patients received 28 days of blinatumomab (replacing induction/early intensification block 1), followed by early intensification and consolidation chemotherapy. QoL was measured with the Pediatric Quality of Life Inventory (PedsQL) 3.0 cancer module. Child self-report was used for patients aged 5–18 years and parent proxy-report for patients aged 2–18 years. Patients who received blinatumomab and their parents would complete the questionnaires at baseline (after 15 days of chemotherapy induction), during or after blinatumomab treatment (d33), after early intensification block 1 (d45), and after early intensification (d60). We also collected QoL from the patients who received only chemotherapy during the same period at the same time points. The PedsQL 3.0 cancer module consists of Pain and hurt, Nausea, Procedural anxiety, Treatment anxiety, Worry, Cognitive problems, Perceived physical appearance, Communication subscale scores, and a total score (sum of all the items over the number of items answered on all the scales). All PedsQL scores range from 0 to 100, with higher scores indicating better QoL. Results: From November 2024 to July 2025, 73 patients aged 2–18 years were included in the analysis, with 54 patients having an assessment at baseline and at least one postbaseline visit. There were 29 patients in the blinatumomab group and 25 in the chemotherapy group. The median age in the blinatumomab group was 5 years (range 2-15), with 4 HR and 25 MR cases, and 18 patients receiving outpatient blinatumomab infusions. The median age in the chemotherapy-only group was 7 years (range 2-14), with 15 standard-risk and 10 MR cases. In the child self-report, the blinatumomab group showed improvements in PedsQL total scores with mean changing from baseline to d33, d45, and d60 of +10.15, +5.63, and +2.53. Due to subsequent chemotherapy, mean changes of total scores from baseline to d45 and d60 decreased. The greatest improvements were observed in mean changes from baseline to d33 for Pain and Hurt (+17.31), Nausea (+11.88), Worry (+6.25), Cognitive problems (+20.19), Perceived Physical Appearance (+31.25), and Communication (+12.5). The chemotherapy group showed minor changes from baseline to d33, d45 of +0.27, +5.53 and decreased by -5.29 in d60, respectively, with deterioration in Nausea (-10.71) after induction therapy. Similar trends were observed in parent proxy-report, with the blinatumomab group showing mean changes from baseline to d33, d45, and d60 of +9.59, +5.93, and +3.85. The greatest improvements were observed in mean changes from baseline to d33 for Pain and Hurt (+8.21), Nausea (+6.82), Procedural Anxiety (+8.39), Treatment Anxiety (+16.67), Worry (+17.16), Perceived Physical Appearance (+10.29), and Communication (+11.27). The chemotherapy group showed mean changes from baseline to d33, d45, and d60 of -2.83, +2, and -0.88, respectively, with deterioration in Nausea (-10.72), Perceived Physical Appearance (-9.26), and Communication (-11.27) after induction therapy. Conclusion: Preliminary analysis found that QoL deteriorated after continued chemotherapy induction, particularly in terms of Nausea, Perceived physical appearance, and Communication. However, substituting part of the induction or early intensification chemotherapy with blinatumomab significantly improves QoL, with notable increases in multiple terms. This suggests that blinatumomab can enhance patients' QoL compared to chemotherapy. The study is ongoing, and more patients will be enrolled.

Background B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common malignancy in children. Blinatumomab is a bispecific T-cell engager (BiTE) antibody targeting CD3 and CD19. T-cell function is considered a critical factor influencing the efficacy of Blinatumomab. This study analyzed functional dynamics in peripheral T cells of newly diagnosed BCP-ALL patients during Blinatumomab treatment using full-spectrum flow cytometry, aiming to identify immune patterns linked to treatment outcomes and support personalized immunotherapy optimization. Methods The study enrolled pediatric BCP-ALL patients from the CCLG-ALL 2018 protocol, including intermediate-risk (MR, day 15 MRD 1-10%) and high-risk (HR, MRD ≥10% or high-risk genetics) groups. PBMNCs were collected at baseline and multiple time points (days 2, 7, 14 for MR; plus days 21, 28 for HR). A 23-color full-spectrum flow cytometry panel analyzed 23 T-cell subsets and expression of 4 activation (CD69, CD80, CD86, Granzyme B) and 7 exhaustion markers (PD-1, TIM-3, LAG-3, TIGIT, CTLA-4, BTLA, CD160). Results A total of 42 pediatric BCP-ALL patients treated with blinatumomab were included in the analysis (28 MR and 14 HR). Full-spectrum flow cytometry was performed at 185 time points. The median age was 6 years (range: 1–15), and 59.5% (25/42) were male. High-risk genetic alterations were present in 64.3% (27/42) of patients. The median bone marrow (BM) blast burden at enrollment was 5.51% (range: 0.02%–50.38%). Following treatment, all 14 HR patients and 21 MR patients achieved deep MRD negativity, while 7 MR patients failed to reach deep molecular remission (NGS MRD ≥10⁻⁶). On day 2, CD3⁺ T-cell proportions declined significantly in both risk groups before gradually increasing and eventually surpassing baseline levels. Notably, MR patients who failed to achieve deep remission showed a more pronounced drop in CD3⁺ T cells on day 2, suggesting lower baseline T-cell counts or impaired functionality, potentially leading to early exhaustion or rapid recruitment to leukemia sites. Importantly, the dynamic trend of CD3⁺ T cells closely mirrored that of CD8⁺ T cells, both showing early depletion followed by gradual recovery. This similarity likely reflects the dominant contribution of CD8⁺ cytotoxic T cells within the total CD3⁺ T-cell population during the early phase of blinatumomab-induced immune activation, especially given that CD8⁺ cells are primary mediators of cytotoxicity. Treatment-responsive patients exhibited higher baseline levels of central memory (Tcm) and effector memory (Tem) T cells, while non-responders had significantly lower levels, suggesting that pre-existing memory T-cell pools may facilitate more rapid and effective immune engagement. Effector T cells (Teff) increased sharply on day 2 in responders, then declined toward baseline. In contrast, non-responders showed delayed Teff activation (day 7), indicating suboptimal immune priming. CD4⁺ T cells and NK cells increased slightly on day 2 and then stabilized. In MR patients, Treg levels rose progressively, but with smaller increases in those achieving deep remission, suggesting that excessive immunosuppression may impede response. In HR patients, Tregs peaked on day 14 and subsequently declined, indicating transient immunosuppression followed by immune rebalancing. Notably, expression of activation markers (CD69, CD80, CD86) and Granzyme B on CD3⁺ and CD8⁺ T cells peaked on day 2 and then declined to near-baseline levels, further confirming that T cells were rapidly activated to exert anti-tumor effects, followed by a regulatory phase to maintain immune homeostasis. NK and NKT cells maintained high Granzyme B expression throughout treatment, suggesting sustained cytotoxic potential and indirect activation. Meanwhile, MDSCs and monocytes remained elevated, indicating a persistently immunosuppressive microenvironment. ConclusionsThis study reveals the complex dynamic changes of T-cell subsets during Blinatumomab treatment and identifies multiple immune markers closely associated with therapeutic efficacy. Early alterations in T-cell subsets, including activation and exhaustion markers, can serve as potential indicators for predicting treatment response and assessing immune status. These findings provide important references for efficacy monitoring and optimization of personalized immunotherapy strategies in pediatric BCP-ALL.

To identify early risk factors for disseminated intravascular coagulation (DIC), particularly severe DIC (grade 4-5), in paediatric acute promyelocytic leukaemia (APL). One hundred and eighty-six paediatric APL patients enrolled in the Chinese Children Leukemia Group (CCLG)-APL 2016 study across 38 hospitals nationwide were grouped based on the occurrence and severity of DIC during induction therapy. DIC occurred in 52.2% of patients during induction therapy, with 7.5% developing grade 4-5 DIC. Significant differences were observed between the DIC and non-DIC groups in the proportion of patients with initial white blood cells (WBC) ≥5 × 109/L, initial platelets (PLT) ≤26 × 109/L and arsenic trioxide (ATO) use (p < 0.05). Multivariate analysis identified initial PLT ≤26 × 109/L (p = 0.002, odds ratio [OR] = 2.679, 95% confidence interval [CI]: 1.438-4.992) as an independent risk factor, while induction therapy using realgar-indigo naturalis formula (RIF) was a protective factor (p = 0.030, OR = 0.465, 95% CI: 0.232-0.929). Further analysis revealed that Fms-like tyrosine kinase 3 (FLT3) mutation (p = 0.023, OR = 11.742, 95% CI: 1.405-98.149), initial PLT ≤26 × 109/L (p = 0.017, OR = 13.784, 95% CI: 1.598-118.905) and initial bone marrow blasts ≥90% (p = 0.030, OR = 5.289, 95% CI: 1.178-23.744) were significant risk factors for grade 4-5 DIC. Initial WBC ≥5 × 109/L and PLT ≤26 × 109/L are associated with an increased risk of DIC, with PLT ≤26 × 109/L as an independent risk factor. Compared with ATO, RIF is a protective factor during induction therapy. Additionally, FLT3 mutation, PLT ≤26 × 109/L and initial bone marrow blasts ≥90% are independent risk factors for grade 4-5 DIC.

Background Infant acute lymphoblastic leukemia (IALL) is highly aggressive with poor prognosis, representing a key focus and challenge in pediatric leukemia research globally. Multiple center studies have demonstrated the favorable efficacy of blinatumomab in adult and pediatric ALL. We report the efficacy and safety of frontline blinatumomab for infant ALL patients in our center. Methods We retrospectively analyzed 11 IALL patients treated with blinatumomab as frontline treatment at Beijing Children's Hospital, Capital Medical University, between March 2023 and March 2025. Inclusion criteria included: (1) age at diagnosis < 12 months, (2) B-cell precursor acute lymphoblastic leukemia, and (3) never received any IALL-related treatment. All patients were risk-stratified according to the Chinese Children's Leukemia Group 2018-ALL (CCLG-2018-ALL) protocol, and blinatumomab was administered at induction treatment, consolidation treatment, and post-consolidation intensification stages. All patients received cycles of blinatumomab therapy ranging from half a cycle (14 days) to 3 cycles: 3 patients completed 3 cycles, 4 patients received 2 cycles, and 2 patients were treated for half a cycle. Among the high-risk patients (n=8), 5 pts received concomitant venetoclax (BCL2 inhibitor) during their first blinatumomab cycle. MRD was assessed by MFC monitoring leukemia-associated aberrant immunophenotypes (sensitivity 1×10⁻⁴), PCR detecting fusion gene (sensitivity 1×10⁻5), and next-generation sequencing (NGS) of immunoglobulin genes (sensitivity 1×10⁻⁶). Adverse events were assessed according to CTCAE 5.0. Results This study included 11 patients with a median age of 8.5 months (range: 1.3-11.5 months), of whom 7 (63.6%) were female. According to risk stratification, 3 cases (27.3%) were classified as intermediate-risk (IR) and 8 (72.7%) as high-risk (HR). All 8 HR patients harbored KMT2A rearrangements, including 5 patients with MLL::AF4 fusion, 2 patients with MLL::ENL, and 1 patient with MLL::AF9. Of the 3 IR patients, 1 patient carried PAX5::PROSER1 fusion. Median WBC at diagnosis 31.06×109/L (1.42, 346.21); 1pts with CNS3, 4pts with CNS2 at diagnosis. All patients achieved bone marrow complete remission (CR) after 15 days of induction therapy, and 2 patients achieved minimal residual disease (MRD) negativity. Among the 8 patients who initiated blinatumomab immunotherapy during induction (after induction day 15, replacing the subsequent 2-week phase of induction), 1 patient had negative bone marrow MRD on day 15 of induction; the remaining 7 patients achieved MRD negativity after 14 days of blinatumomab treatment. All pts maintained CR until the end of follow-up, with the longest event-free survival (EFS) of 20 months in the youngest patient. Of the 3 patients who started blinatumomab after induction, 1 patient had persistent MRD negativity since day 15 of induction with an EFS of 23 months; the other 2 patients, whose MRD remained positive after induction, both achieved MRD negativity after blinatumomab treatment. One of these 2 patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) following consolidation therapy, while the other patient experienced relapse during consolidation with an EFS of 12 months, after which allo-HSCT was performed. Adverse events during the first blinatumomab treatment cycle included respiratory infections (4 patients), diarrhea (3 patients, grade 2), elevated transaminases (1 patient grade 2, 1 patient grade 3), and 1 patient with PICC-associated bloodstream infection. Treatment-related cytokine release syndrome (CRS) of grade 1 occurred in 4 pts, with no severe CRS events or immune effector cell-associated neurotoxicity syndrome (ICANS) observed. Conclusions This retrospective study suggests that blinatumomab combined with chemotherapy can greatly eliminate leukemia cells and achieve favorable remission in infant ALL. Early administration of blinatumomab may lead to early negativity of MRD, and the adverse reactions are manageable. It is expected that new immunotherapeutic agents will change the treatment predicament of childhood ALL, especially infant ALL. However, large-scale clinical data and longer follow-up are still needed for verification.

USP7 alterations in pediatric T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) remains incompletely understood. We investigated the clinical features and long-term outcomes associated with USP7 mutations in a cohort of 313 pediatric T-ALL/LBL patients. USP7 and NOTCH1 mutations were detected by Sanger sequencing and their association with prognosis were analyzed. Cox regression and nomogram models were used to evaluate prognostic importance. We identified 12 patients with USP7 heterozygous mutations (10 T-ALL, 2 T-LBL) with older age and higher proportion of not remission at day 15 morphological evaluation. Patients with USP7 mutation showed significantly worse event-free survival (EFS) and overall survival (OS) compared to wild-type cases, both in T-ALL and combined T-ALL/LBL cohorts. Concurrent analysis of USP7 and NOTCH1 mutations revealed USP7mutNOTCH1wt genotype was associated with the worst, whereas USP7wtNOTCH1mut was linked to the best EFS and OS in both T-ALL and T-ALL/LBL groups. USP7 mutation, pre-consolidation MRD ≥ 10−4 and CNS leukemia were independent adverse factors for EFS, and the former two were also predictors for OS. USP7 mutation status was validated as the most influential prognostic factor, with prediction models including USP7 status showing enhanced accuracy. In conclusion, USP7 mutations define a subset of T-ALL/LBL patients with adverse outcomes on conventional intensive treatment.

Introduction: Blinatumomab, a bispecific antibody that directs CD3 T cells to CD19 leukemic cells, shows promise in treating pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Samples for this study were obtained from children enrolled in an open-label, single-arm clinical trial (ChiCTR2400083570) that advances blinatumomab to the induction chemotherapy stage. Despite its potential, not all patients respond well to this treatment, making it crucial to elucidate the specific mechanisms underlying the varied responses to blinatumomab in BCP-ALL. Methods: Seven pediatric BCP-ALL patients with positive minimal residual disease (MRD, ≥1%) after 15 days of routine induction chemotherapy were included in our study and subsequently received a 28-day blinatumomab treatment. Bulk RNA-sequencing (RNA-seq) was used to determine the baseline cellular abundance of BCP-ALL. Single-cell RNA-sequencing (scRNA-seq) was performed to characterize the cellular dynamics of the B and T cells, as well as the B-cell and T-cell receptor (BCR/TCR) repertoires in BCP-ALL patients before, and on day 14 and 28 during blinatumomab treatment. Results: Among 7 patients, 2 patients (P-1 and P-2) remained MRD+ at all surveillance time points (insensitive group), while the other 5 patients achieved MRD- (MFC MRD<10-4 or NGS MRD<10-6) on day 14 (P-3) or day 28 (P-4, P-5, P-6 and P-7) following blinatumomab treatment (sensitive group). Using a Bayesian method with scRNA-seq as prior information, we predicted the cellular composition of B-ALL from bulk RNA-seq data. Our findings indicated that the insensitive group had higher levels of hematopoietic stem cells (HSC) and common lymphoid precursors (CLP) compared to the sensitive group. This suggests that elevated proportions of HSC and CLP are strongly associated with a reduced response to blinatumomab. Pseudo-time analysis revealed that B cells in the sensitive group followed a normal developmental trajectory, where HSC differentiated into pro-B, pre-B, immature B, or plasma cells. In contrast, B cells in the insensitive group displayed an abnormal trajectory, with differentiation predominantly reverting from plasma or immature B cells back to HSC. Similarly, T-cell subsets exhibited comparable differences in developmental trajectories between the sensitive and insensitive groups. During 28-day blinatumomab treatment, the percentage of effector T cells (Teff) in the sensitive group initially decreased but then increased, while in the insensitive group, the percentage of Teff continuously declined. Both groups showed a rise and subsequent fall in the proportion of exhausted T cells (Tex). Notably, we identified two distinct Tex clusters: CXCR6-Tex and MKI67-Tex. On day 14, the abundance of CXCR6-Tex and MKI67-Tex was significantly higher in the sensitive group compared to the insensitive group. Shared TCR clones and similar core transcription factors (TFs) expression patterns between the Teff and CXCR6-Tex, as well as CXCR6-Tex and MKI67-Tex, support the presence of a differentiation trajectory. We hypothesize that blinatumomab treatment may cause some Teff to first convert to CXCR6-Tex, with a subset then further converting to MKI67-Tex. Interestingly, MKI67-Tex exhibited high expression of genes related to the TCR signaling pathway and cytotoxic effector molecules, including granzymes B, A, and K, suggesting that MKI67-Tex may play a role in killing leukemic cells. Conclusion: This study illuminates cellular dynamics during blinatumomab treatment and provides new insights into its mechanism of action in BCP-ALL. Detailly, on day 14, leukemic cells are still present in the majority of patients (6/7, 85.7%), indicating that extending blinatumomab treatment to 28 days is necessary for BCP-ALL patients who do not achieve MRD- after 15 days of routine induction chemotherapy. Blinatumomab prompts Teff cells to target leukemic cells, leading to the conversion of some Teff to Tex. Notably, MKI67-Tex, identified in our study, also exhibits anti-tumor effects. Additionally, insensitive group shows higher levels of stem cell infiltration and abnormal differentiation trajectories, which may be a potential mechanism of resistance to blinatumomab.

Purpose: This study aimed to investigate the efficacy and safety of adding blinatumomab to first-line treatment in Chinese children with B-cell acute lymphoblastic leukemia (B-ALL) who were either chemotherapy-intolerant or classified as intermediate-risk/high-risk. Methods: The clinical data of children with newly diagnosed B-ALL treated with blinatumomab plus chemotherapy as first-line treatment were retrospectively analyzed. Newly diagnosed B-ALL children who were chemotherapy-intolerant or classified as intermediate-risk/high-risk received one to two cycles of blinatumomab therapy (15µg/m2, 14-28 days) in addition to the Chinese Children's Leukemia Group(CCLG)-B-ALL-2018 regimen. Following blinatumomab treatment, chemotherapy was continued, or allogeneic hematopoietic stem cell transplantation was performed for those with indications. Minimal residual disease (MRD) remission, as assessed by multiparameter flow cytometry (MFC-MRD), was defined as the presence of leukemic blasts with MRD <0.01% in bone marrow. MRD remission, measured by next-generation sequencing and flow cytometry, was defined as the presence of leukemic blasts with MRD <0.0001% in bone marrow. Results: From March 2021 to September 2023, 90 children with newly diagnosed B-ALL were treated with blinatumomab. Among them, 49 (54.4%) with chemotherapy intolerance, 48 (53.3%) were in the intermediate-risk group, and 32 (35.6%) were in the high-risk group. The median time from diagnosis to the start of blinatumomab was 10.8 (range, 0.7-25.9) months. Of these patients, 19 (21.1%) received blinatumomab after induction chemotherapy, 11 (12.2%) during consolidation chemotherapy, and 60 (66.7%) after consolidation chemotherapy. Ninety children completed a total of 112 cycles of infusion, 68 (73.9%) in one cycle and 22 (24.1%) in two cycles, with a median duration of 28 days (range, 2-56 days). The complete remission (CR)/complete remission with incomplete hematologic recovery (CRi) rate after one cycle of blinatumomab was 100.0%, MRD remission rate was 94.4%, and MFC-MRD remission rate was 98.9%. Seven patients were treated with allogeneic hematopoietic stem cell transplantation during consolidation therapy, specifically one infant with MLL-AF4, three with persistently positive BCR-ABL1 fusion genes, two with persistently positive NGS-MRD, and one with EBF1-PDGFRB that could not be tolerated chemotherapy and blinatumomab because of G4 ICANS. After a median follow-up of 26.8 months, 2-year event-free survival (EFS) rate was 97.8% ± 1.6%, 2-year overall survival (OS) rate was 100%, and 2-year cumulative incidence of relapse (CIR) was 2.2% ± 1.6%. Compared with 212 historical control patients treated under the CCLG-B-ALL-2018 protocol and matched for sex, age, and white blood cell count at onset of leukemia, the 2-year EFS was significantly higher in the blinatumomab group (97.8 ± 1.6% vs. 92.3 ± 1.9%, p=0.047). Subgroup analysis showed that high-risk children in the blinatumomab group had significantly higher 2-year EFS and 2-year OS compared to those in the control group (2-year EFS: 93.6 ± 4.3% vs. 76.5 ± 6.9%, p=0.040; 2-year OS: 100% vs. 89.2 ± 5.1%, p=0.046). When stratified by genetic risk, high-risk children in the blinatumomab group had a higher 2-year EFS than those in the control group (97.3 ± 2.7% vs. 83.0 ± 4.7%, p=0.045). Additionally, children with MRD >0.1% at the end of induction (day 33) in the blinatumomab group had a higher 2-year EFS compared to those in the control group (94.4 ± 5.4% vs. 65.7 ± 11.5%, p=0.025). Adverse events associated with blinatumomab were tolerable, with treatment discontinuation in 6 (6.7%) patients, including G3 infection-related events in 3 (3.3%) patients and G3/4 immune effector cell-associated neurotoxicity syndrome (ICANS)-related epilepsy in 3 (3.3%) patients. Conclusion: In children with chemotherapy-intolerant or intermediate-risk/high-risk B-ALL, the addition of blinatumomab to first-line chemotherapy can enhance the deep remission rates and improve survival, particularly in high-risk patients and those with high MRD after induction regimen.

Introduction: B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most prevalent childhood malignancy. T cell-based bispecific monoclonal antibody blinatumomab shows substantial clinical efficacy; however, some children exhibit suboptimal immune responses, leading to reduced effectiveness. T lymphocyte function is considered as one of the critical determinants of blinatumomab's efficacy. This study investigated the dynamics of T cell function during blinatumomab treatment, providing significant theoretical and practical insights for the clinical treatment of pediatric BCP-ALL. Methods: We will recruit 40 children with BCP-ALL who are identified as high-risk for relapse, either due to minimal residual disease (MRD) ≥1% or high-risk genetic adverse characteristics, following 15 days of routine induction chemotherapy. Subsequently, these children received a continuous infusion of blinatumomab, based on clinical experience with induction chemotherapy. Peripheral blood mononuclear cells (PBMNCs) were collected before the blinatumomab treatment and on days 2, 7, and 14 for patients classified as medium risk, or on days 2, 7, 14, 21, and 28 of high risk. Both groups included children with good and poor responses to blinatumomab. The proportion of CD3+ (total T lymphocytes), CD4+ (T helper lymphocytes), CD8+ (T cytotoxic lymphocytes) and its subsets(naïve T, central memory [TCM], effector memory [TEM], effector memory cells re-expressing CD45RA [TEMRA]), γδT cells, CD4-CD8- T, CD4+CD8+ T, Treg cells, NK cells, NKT cells, and every subsets'expression of the exhaustion molecules (PD-1, TIM-3, LAG-3, TIGIT, CTLA-4, BTLA and CD160) and activation molecules (CD69, CD80, CD86, and Granzyme B) were determined by the full-spectrum flow cytometry with total 23 cell markers in one tube. Results: Until now, 4 patients (3 with medium risk and 1 with high risk) have been enrolled; they have responded well to blinatumomab treatment, achieving MRD negativity. Patients with medium-risk received a 14-day blinatumomab treatment, while the high-risk underwent a 28-day blinatumomab, following 15 days of routine induction chemotherapy. The percentage of CD3+ T cells declined on day 2 (medium-risk: from 54.92% to 46.29%; high-risk: from 73.94% to 32.51%). Subsequently, the percentage rose above the baseline in both groups (medium-risk: from 46.29% to 90.2% to 86.94%; high-risk: from 32.51% to 89.88% to 94.65% and maintaining this level). The percentage of CD8+ T cells declined on day 2 (medium-risk: from 52.57% to 36.98%; high-risk: from 66.33% to 51.21%). In the medium-risk group, the percentage returned to baseline (from 36.98% to 54.89% to 45.33%), whereas in the high-risk group, it further reduced over subsequent time points. The proportion of CD4+ T cells increased on day 2 in both groups (medium-risk: from 38.56% to 43.45%; high-risk: from 16.75% to 31.03%). It then decreased to baseline on day 7 in the medium-risk group, before increasing again on day 14. In contrast, the percentage continued to ascend at all surveillance time points in the high-risk group, which was different from the trend observed for CD3+ and CD8+ T cells. The percentage of exhausted molecules (Tim3 and PD-1) of CD3+ T cells decreased on day 2 and then arose. The percentage of activated molecules (CD69, CD80, CD86, and Granzyme B) of CD3+ T cells increased on day 2 and then decreased. A similar phenomenon was observed in CD8+ T cells in the medium-risk group. We also noted that Tcm started to decrease on day 7, while Tem and Tex rose instead. The expression of CD69, CD80, and CD86 of Tex arrived at its highest level on day 2, then fell below baseline. Treg cells and monocytes were always above the baseline levels from day 2 to the end of the treatment. No obvious changes were observed in γδT, CD4-CD8- T, CD4+CD8+ T, NK, and NKT cells in the current data. Conclusion: Our data demonstrated the dynamics of T cell subsets in BCP-ALL during continuous infusion of blinatumomab. The trends of CD3+ T cells and their expression of exhaustion and activation molecules were coincident with CD8+ T cells throughout blinatumomab treatment. The relationship between the dynamics of T cell function and clinical efficacy (complete remission, MRD negative rate) warrants further exploration, which contributes to identifying the predictive biomarker and guiding the precision treatment of clinical immunotherapy. This study is ongoing with a larger sample size.

The prognosis of paediatric acute promyelocytic leukaemia (APL) has been significantly improved with all-trans-retinoic acid (ATRA) and arsenic.1, 2 However, the early death within 30 days of induction therapy continues to present a significant challenge in achieving successful outcomes for all patients with APL.3 As such, the rational utilization of cytoreduction therapy plays a crucial role in reducing early mortality rates of APL.4 Since traditional cytoreduction agents can lead to severe disseminated intravascular coagulation (DIC) and even death, the development of novel cytoreduction agents to minimize early mortality is urgently needed. Venetoclax, a BCL-2 inhibitor, has been demonstrated effective for adult relapsed/refractory APL.5 However, there are no reports on the efficacy and safety of venetoclax in paediatric APL. In this study, we first used low-dose venetoclax as a cytoreduction therapy for APL and obtained a very encouraging result. From December 2021 to March 2023, 11 children with APL were enrolled (Table 1), and treated with arsenic combined with ATRA for induction and consolidation therapy (ChiCTR2100052966) (Figure S1), which was approved by the Medical Ethics Committee of Beijing Children's Hospital, Capital Medical University. Additionally, an informed consent form for the use of venetoclax beyond the instructions was signed by all the patients or their legal guardians. Of the 11 patients with APL, 6 (Cases 1–6) were treated with traditional cytoreduction therapy, and 5 patients (Cases 7–11) were treated with venetoclax cytoreduction therapy (Table 1). Eight of the 11 patients achieved haematological complete remission (HCR) on Day 28 of induction, and all patients achieved molecular complete remission (MCR) on Day 28 of the first consolidation, except for one (Case 1), who finally achieved MCR on the day of repeated consolidation. The median times to achieve HCR and MCR were 28 days (26–69 days) and 68 days (42–104 days) respectively. None of the children had serious adverse events during induction (Table S1). In contrast to conventional cytoreduction therapy, the use of venetoclax cytoreduction therapy resulted in the suspension of ATRA and arsenic in only one out of the five patients, primarily due to suspected or confirmed differentiation syndrome (DS). Conversely, in the group treated with conventional cytoreduction, ATRA and arsenic were suspended in five of the six patients. All patients treated with venetoclax achieved HCR on Day 28 of induction, but only three of the six patients treated with traditional cytoreduction achieved HCR on Day 28 of induction. In addition, leucocyte counts decreased to trough levels on Days 4–5 after one to three doses of venetoclax (Figure 1). Compared with the Case 2 treated with traditional cytoreduction, the Case 8 with venetoclax cytoreduction, who showed consistent clinical features at diagnosis, had no significant increase in leucocyte counts. Furthermore, there was no need to interrupt targeted therapy due to suspected or confirmed DS. The patient achieved HCR on Day 28 of induction and MCR on Day 28 of consolidation. The primary cause of early mortality in APL is typically life-threatening coagulopathy4 with a variety of clinical manifestations, including life-threatening bleeding and venous or arterial thrombosis.6 This study reveals that thrombosis may be an underestimated and potentially life-threatening manifestation of coagulopathy in APL patients, aligning with previous findings.4 Fortunately, all of patients experiencing life-threatening coagulopathy in our study survived and achieved HCR and MCR during continued consolidation therapy. Moreover, our study suggests that venetoclax as cytoreduction regimen exhibits potential advantages, including reduced reliance on platelet and plasma infusion, and a lower incidence of DS. Thus, compared to traditional cytoreduction, venetoclax may be a more favourable option as a cytoreduction therapy for APL patients. In summary, based on our clinical experience, venetoclax demonstrated effective and safety as a cytoreduction therapy for paediatric APL. However, the further confirmation is required through the expansion of the sample size in future studies. Currently, a prospective study in multiple centres across China, led by our hospital (ChiCTR2300069288), to gather additional evidence and validate these findings. Huyong Zheng designed the study. Peijing Qi, Linya Wang and Hongqiao Li collected the data. Linya Wang and Huyong Zheng wrote the paper. All authors treated the patients and reviewed the paper and gave final approval. This work was supported by the National Natural Science Foundation of China (NSFC) (No. 82070154), Beijing Natural Science Foundation (No. 7222056) and Capital's Funds for Health Improvement and Research (CFH) (No. 2022-1-2091). No potential conflict of interest is reported by any of the authors. The primary treatment of acute promyelocytic leukaemia in this study was based on the CCLGA-APL 2021 protocol (ChiCTR2100052966). Besides, to further validate our findings, a prospective study in multiple centres across China, led by our hospital (ChiCTR2300069288). Figure S1. Figure S2. Table S1. Table S2. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Infantile hepatic hemangioma and hepatoblastoma are the most common benign and malignant tumors of the liver in the neonatal and early childhood periods, respectively. However, the simultaneous occurrence of these 2 tumors in the same liver lesion is very rare. We report a case of a newborn infant diagnosed with a liver mass by ultrasound examination 4 days after birth. Serum alpha-fetoprotein (AFP) was elevated for his age (32,881.7 ng/mL). The liver mass was resected. Macroscopically, an externally protruding mass measuring 6 × 4 × 3.5 cm was identified. Microscopically, we observed the coexistence of infantile hepatic hemangioma and epithelial hepatoblastoma components within the tumor. The infantile hepatic hemangioma component was composed of multiple small vascular channels lined by endothelial cells. In the hepatoblastoma component, tumor cells were arranged in a 2- to 3-cell-thick trabecular formation. Immunohistochemistry indicated that the tumor cells in the infantile hepatic hemangioma component expressed CD34, CD31, FLI1, and ERG, and those in the hepatoblastoma component expressed hepatocyte, keratin AE1/AE3 and keratin 8, glypican 3, glutamine synthetase, and AFP. Pathological examination confirmed the presence of an infantile hepatic hemangioma combined with epithelial hepatoblastoma (fetal type). The boy did not undergo chemotherapy after the operation. Regular follow-up through serum AFP levels and liver ultrasound for 16 months to date show that the serum AFP levels decreased continuously to normal levels, with no signs of tumor recurrence or metastasis. The coexistence of infantile hepatic hemangioma and hepatoblastoma is rare. Hepatoblastoma should be considered in neonates with liver tumors and elevated AFP.

Allogeneic hematopoietic stem cell transplantation (HSCT) is an effective treatment for acute myeloid leukemia (AML). Pediatric patients with AML who relapse after HSCT have an extremely poor prognosis. We performed a retrospective study of pediatric patients diagnosed with AML from August 2015 to October 2019 who were treated with HSCT. Kaplan-Meier analyses were used to evaluate overall survival (OS), event-free survival (EFS), and cumulative recurrence rate (CRR). Cox regression analysis was used to determine the association between the baseline characteristics and relapse. A total of 37 pediatric patients met the inclusion criteria. Twenty-eight (75.7%) patients survived, and 9 (24.3%) patients died. The OS rates of AML patients treated with HSCT were 89.2% ± 5.1%, 75.7% ± 7.1%, and 75.7% ± 7.1% at 1, 3, and 5 years, respectively, and the CRRs were 11.4% ± 5.4%, 24.7% ± 7.7%, and 33.1% ± 10.4% at 1, 3, and 5 years after HSCT, respectively; four of nine children who relapsed after transplantation died. Induction with etoposide rather than homoharringtonine and fungal infections could be high-risk factors for recurrence after transplantation. The association between homoharringtonine-based induction therapy and a low recurrence rate persisted after adjusting for age, sex, risk stratification, fusion genes, and fungal infections. This study clarifies the clinical features and poor prognosis of post-transplant relapse in pediatric AML and indicates the urgent need for effective therapy for patients who relapse after HSCT.

PURPOSEHomoharringtonine (HHT) is commonly used for the treatment of Chinese adult AML, and all-trans retinoic acid (ATRA) has been verified in acute promyelocytic leukemia (APL). However, the efficacy and safety of HHT-based induction therapy have not been confirmed for childhood AML, and ATRA-based treatment has not been evaluated among patients with non-APL AML.PATIENTS AND METHODSThis open-label, multicenter, randomized Chinese Children's Leukemia Group-AML 2015 study was performed across 35 centers in China. Patients with newly diagnosed childhood AML were first randomly assigned to receive an HHT-based (H arm) or etoposide-based (E arm) induction regimen and then randomly allocated to receive cytarabine-based (AC arm) or ATRA-based (AT arm) maintenance therapy. The primary end points were the complete remission (CR) rate after induction therapy, and the secondary end points were the overall survival (OS) and event-free survival (EFS) at 3 years.RESULTSWe enrolled 1,258 patients, of whom 1,253 were included in the intent-to-treat analysis. The overall CR rate was significantly higher in the H arm than in the E arm (79.9% v 73.9%, P = .014). According to the intention-to-treat analysis, the 3-year OS was 69.2% (95% CI, 65.1 to 72.9) in the H arm and 62.8% (95% CI, 58.7 to 66.6) in the E arm (P = .025); the 3-year EFS was 61.1% (95% CI, 56.8 to 65.0) in the H arm and 53.4% (95% CI, 49.2 to 57.3) in the E arm (P = .022). Among the per-protocol population, who received maintenance therapy, the 3-year EFS did not differ significantly across the four arms (H + AT arm: 70.7%, 95% CI, 61.1 to 78.3; H + AC arm: 74.8%, 95% CI, 67.0 to 81.0, P = .933; E + AC arm: 72.9%, 95% CI, 65.1 to 79.2, P = .789; E + AT arm: 66.2%, 95% CI, 56.8 to 74.0, P = .336).CONCLUSIONHHT is an alternative combination regimen for childhood AML. The effects of ATRA-based maintenance are comparable with those of cytarabine-based maintenance therapy.

Objective:To evaluate the real-world efficacy and safety of sofosbuvir and velpatasvir (SOF/VEL) tablets in the treatment of Chinese patients with chronic HCV infection.Methods:An open-label, single-center, prospective clinical study was conducted in a county in northern China. A total of 299 cases were enrolled. Of these, 161 cases with chronic hepatitis C and 73 cases with compensated cirrhosis received SOF/VEL for 12 weeks. 65 cases with decompensated cirrhosis received SOF/VEL combined with ribavirin for 12 weeks (22 cases) or SOF/VEL for 24 weeks (43 cases). Virological indicators, liver and renal function indexes, and liver stiffness measurement were detected at baseline, the fourth week of treatment, the end of treatment, and the 12-weeks of follow-up. Adverse reactions and laboratory abnormalities were observed during the course of treatment . The primary endpoint was undetectable rate of HCV RNA (SVR12) at 12 weeks of follow-up with the use of modified intention-to-treat (mITT) approach. Measurement data between two groups were compared using t-test. One Way ANOVA was used for comparison between multiple groups. Enumeration data were analyzed by chi-square test or Fisher's exact test.Results:291 cases had completed treatment. HCV RNA was undetectable after 12 weeks of follow-up, and the SVR12 rate was 97.3% (95% confidence interval: 95.4%-99.3%). Among them, 97.4% of genotype 1b, 96.4% of genotype 2a, and 100% of those with undetected genotype achieved SVR12. The SVR12 rates in patients with chronic hepatitis C, compensated and decompensated liver cirrhosis were 98.1%, 98.6% and 93.8%, respectively. An improvement in alanine aminotransferase, aspartate aminotransferase and other liver biochemical indicators accompanied with virological clearance and reduced liver stiffness measurement was observed in patients with compensated cirrhosis, with statistically significant difference. There was no significant abnormality in renal function before and after treatment. The most common adverse reactions were fatigue, headache, epigastric discomfort and mild diarrhea. The overall adverse reactions were mild. One patient died of decompensated liver cirrhosis combined with massive upper gastrointestinal bleeding, which was unrelated to antiviral treatment. Four patients discontinued treatment prematurely due to adverse events. Relapse was occurred in four cases, and drug-resistance related mutations were detected in three cases.Conclusion:Sofosbuvir and velpatasvir tablets in Chinese HCV-infected patients with different genotypes, different clinical stages or previously treated with pegylated interferon combined with ribavirin resulted in higher SVR12, indicating that the treatment safety profile is good.

Objective: Pancreatitis in children with acute lymphoblastic leukemia and acute myeloid leukemia may cause discontinuation of chemotherapy, thus adversely affecting treatment outcomes. Enteral nutrition (EN) is recommended for acute pancreatitis. The optimal use of EN for leukemia-related pancreatitis is under debate. The aim of this study was to determine the clinical efficacy of EN for children with leukemiarelated pancreatitis.Methods: Medical records of 53 children with characteristics of leukemia-related pancreatitis were abstracted retrospectively. Considering specific outcome variables, the EN-associated factors improving treatment were analyzed. Enzyme and albumin changes during the 14-day follow-up period were also analyzed, to test for the safety of EN.Results: Early EN was found to be a protective factor from secondary infection and significant weight loss. Jejunal EN was related to higher risk for enzyme elevation relapse compared with oral EN. Patients with severe pancreatitis had lower risk for significant weight loss but higher risk for abnormal glucose levels than their counterparts. EN type had a significant effect on lipase change, and early EN had interactive effects by time on amylase and lipase changes.Conclusions: Early EN within 7.5 days could reduce the risk for secondary infection and significant weight loss for pediatric leukemia-related pancreatitis, with decreased serum amylase and lipase levels, in a safe and effective manner. Beneficial effects of EN within 72 h were not observed.(c) 2022 Elsevier Inc. All rights reserved.

Aim: To evaluate the association between SLCO1B1 polymorphisms and elimination/toxicities of high-dose methotrexate (MTX). Methods: SLCO1B1 rs11045879 and rs4149056 polymorphisms were retrospectively genotyped in 301 children with newly diagnosed acute lymphoblastic leukemia. MTX concentration, doses of leucovorin rescue and toxicities were recorded. Results: SLCO1B1 rs11045879C carriers (CC + CT) had higher plasma MTX levels at 96 hr, and longer MTX elimination time. The number of leucovorin rescue doses in rs4149056C carriers (CC + CT) was more than those in TT ones. Moreover, SLCO1B1 polymorphisms were associated with HDMTX toxicities including thrombocytopenia, renal toxicity and anal mucositis, but not associated with MTX level at other time points or delayed elimination. Conclusions: Our data demonstrate that genotyping of SLCO1B1 might be useful to optimize MTX therapy.

Introduction Acute myeloid leukemia (AML) is a heterogeneous group of hematological malignancy. Classical induction therapy of DAE composed of etoposide (VP-16), cytarabine arabinoside (Ara-C) and anthracycline (DNR) is commonly applied in childhood AML, but etoposide has been reported to increase the risk of secondary cancer, especially for AML with MLL rearrangement. Although homoharringtonine (HHT) is commonly used for the treatment of Chinese adult AML, the efficacy and safety of HHT-based induction therapy have not been confirmed for childhood AML. And whether survival of pediatric AML will benefit from maintenance therapy without increasing toxicity is a matter of debate. All-trans retinoic acid (ATRA)-based therapy has been less reported and verified among non-APL AML patients. Here, we seek to evaluate the efficacy and safety of HHT-based induction regimens combined ATRA-based maintenance therapy for Chinese childhood AML (Chinese Clinical Trial Registry: ChiCTR-IPR-15006816). Methods The 2015 open-label, multicenter, randomized Chinese Children's Leukemia Group (CCLG) study was performed across 35 centers in China between July 2015 and October 2019. Newly diagnosed 0- to 18-year-old children with AML were first randomly assigned to receive HHT-based (H arm) or etoposide-based (E arm) induction regimens [HHT (3 mg/m2 per day from days 1 to 5) or VP-16 (100 mg/m2 per day from days 1 to 5) combined with DA regimen (D: 40 mg/m2 per day on days 1, 3 and 5; A: 100 mg/m2 every 12 hours from day 1 to 7)] and then randomly allocated to receive cytarabine-based (AC arm) or ATRA-based (AT arm) maintenance therapy. The primary endpoint is the complete remission (CR) rate after two courses of induction therapy between H arm and E arm. The secondary endpoints include the 3-year overall survival (OS) and 3-year event-free survival (EFS) of patients in the intent-to-treat population among four arms (H+AT arm, H+AC arm, E+AT arm and E+AC arm). What we should explained is that the study was initially designed as a multicenter randomized controlled trial, however, due to a shortage of HHT, which lasted for half a year in some local hospitals, we had to give priority to ensuring patient benefit and assign these patients to the E arm until HHT became available, and then patients in the H arm were supplemented in those hospitals. So patients were unevenly distributed among the four arms. Results We enrolled 1253 intent-to-treat de novo AML patients, of whom 895 were included in the induction therapy analysis, and 554 received maintenance therapy (Figure 1). The median age was 75.0 months (IQR 36.0-118.0), and 57% of the patients were male. The median follow-up time was 29.4 months (IQR 8.4-47.4). 185 of 1253 patients (14.8%) were lost to follow-up, of whom 70.0% patients have been followed for over 12 months. The CR rates were 88.3% in the H arm versus 83.3% in the E arm (p=0.03). The CR rate of patients with t(8;21)/AML1-ETO was higher in the H arm than in the E arm (94.7% vs. 87.5%, p=0.018). According to the intention-to-treat analysis, the 3-year OS and EFS were significantly higher in the H arm than in the E arm [3-year OS: 69.2% vs. 62.8%, p=0.025 (Figure 2); 3-year EFS 61.1% vs. 53.4%, p=0.022]. Among patients who were enrolled in maintenance therapy (per-protocol population), the 3-year EFS (H+AT arm: 70.7%, 95% CI 61.1-78.3; H+AC arm: 74.8%, 95% CI 67.0-81.0, p=0.933; E+AC arm: 72.9%, 95% CI 65.1-79.2, p=0.789; E+AT arm: 66.2%, 95% CI 56.8-74.0, p=0.336) did not differ significantly across the four arms. In subgroup analysis, patients with AML1-ETO positivity in the H+AT arm had significantly better OS (82.4% vs. 66.4%, p=0.043) and EFS (73.6% vs. 52.8%, p=0.013) than those in the E+AC arm. Conclusions Our study demonstrated, in childhood AML, HHT-based induction regimens (DAH) could significantly obtain higher complete remission rate compared with patients who received etoposide-based regimens, especially for those with AML1-ETO positive. And The HTT-based regimen resulted in a significantly improved 3-year OS and EFS compared with VP-16-based regimen. More patients with AML1-ETO positive who took DAH achieved complete remission, and these patients had longer overall survival and event-free survival, than those who took DAE. And ATRA-based maintenance has comparable effects to cytarabine-based maintenance in terms of OS and EFS. ATRA may be an alternative option for pediatric AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Arsenic trioxide (ATO) has been found to be effective in acute promyelocytic leukemia. However, ATO-induced severe cardiotoxicity limits its clinical application. To date, the mechanisms of ATO-induced cardiotoxicity remain unclear. It is hypothesized that ferroptosis may trigger ATO-induced cardiotoxicity; however, this has not yet been investigated. To clarify this hypothesis, rat cardiomyocyte H9c2 cells were treated with ATO with or without ferrostain-1 (Fer-1). The results indicated that ATO exposure induced H9c2 cell death and apoptosis, and the ferroptosis inhibitor Fer-1, administered for 24 h before ATO exposure, suppressed ATO-induced cell death, and apoptosis, as determined by Annexin V-APC/7-AAD apoptosis assay. Furthermore, Fer-1 displayed a cardioprotective effect through inhibiting the ATO-induced production of intracellular reactive oxygen species, improving the ATO-induced loss of the mitochondrial membrane potential, alleviating hyperactive endoplasmic reticulum stress, and alleviating the ATO-induced impairment in autophagy in H9c2 cells. Overall, the cardioprotective effect of Fer-1 against ATO-induced cell injury implies that ATO may trigger ferroptosis to induce cardiotoxicity. These findings lay the foundation for exploring the potential value of ferroptosis inhibitors against ATO-induced cardiotoxicity in the future.